In the early 1930s, Great Britain found itself in a rather precarious position. Military theorists were predicting, quite correctly, that the next war would be dominated by air power, and the ominous threat of aerial bombardment. With Nazi Germany on the rise, the Brits suddenly felt very vulnerable. To address the problem, Britain launched a number of projects in hopes of mitigating the threat — including an effort to develop nothing less than a high-tech "death ray" that could shoot enemy planes out of the sky.

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But even though the project failed to develop such a weapon, it did result in something potentially far more useful — a technological breakthrough that would prove to play an integral role in the British victory over the Nazis during the Battle of Britain.

The Brits had good reason to be worried. The horrors of World War I were still very fresh in their minds, including memories of first-generation German bombers and zeppelins that rained terror from above — with very little in the way of possible countermeasures.

Over the course of just two decades, Britain had lost its unique advantage as an island nation. For centuries the country had defended itself from external attacks with its powerful navy — but new aerial technologies had changed everything.

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Indeed, planes had improved dramatically since the Great War, rendering small-range anti-aircraft guns all but useless. And with enemy airfields as close as a 20 minute flight away, the only conceivable solution was to position fighter planes in the air around the clock to meet an enemy attack — a completely untenable solution.

In 1932, Prime Minister Stanley Baldwin delivered a speech in the House of Commons conceding their predicament, declaring any attempt to thwart incoming aircraft as a waste of valuable time and resources. "It is well for the man in the street to realise that there is no power on Earth that can protect him from being bombed," he said, "the bomber will always get through."

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Preparing for the next war

Not ready to concede defeat so easily, Britain's Air Ministry set up the Committee for the Scientific Survey of Air Defence (CSSAD) in 1934 to consider their options. The initiative was driven by desperation, but also by a sense of unbridled technological optimism. The industrial revolution had fully matured, and with it the advent of unprecedented new technologies. The previous decades had seen the rise of electricity, wireless communications, automobiles, and airplanes. The military in particular had benefited from scientific and technological advances, including the rise of armoured tanks, machine guns, and of course, bomber planes.

The future, therefore, seemed open in terms of what might be possible — a sentiment that empowered scientists and technologists to consider seemingly radical solutions. Given the rapid pace of technological progress, it was reasonable to assume that the next military paradigm changer could be as little as one invention away.

Fueling this sense of possibility was the disturbing rumor that the Nazis had developed a so-called ‘death ray' capable of destroying towns, cities, and people. In turn, the CSSAD was desperate to know whether the Germans were in fact capable of building such a weapon — and whether they might be able to build one themselves.

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To figure this out, the CSSAD assigned the distinguished Oxford-trained chemist Sir Henry Tizard as chair of the program and recruited a number of other talented British academics. Their task was to "consider how far recent advances in scientific and technical knowledge can be used to strengthen the present methods of defence against hostile aircraft." Among their tasks, they were asked to assess the possibility of producing a particle beam or electromagnetic weapon that could either fry an enemy pilot in the cockpit, detonate a plane's bombs, or incinerate an aircraft as it flew overhead.

Needless to say, the team was unable to come up with anything. So, in an effort that pre-dated the X-Prize by a half-century, the Air Ministry offered a £1,000 reward to anyone who could build a death ray that could kill sheep from a distance of 100 yards.

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No one claimed the prize.

In turn, the Brits got more serious. In January 1935, H. E. Wimperis, the director of Scientific Research at the Air Ministry, assigned the Superintendent of the Radio Research Station, Robert Watson-Watt, to advise the government on the "practicability of proposals of the type colloquially called ‘death ray'".

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To assess the feasibility of such a weapon, Watson-Watt assigned his assistant, Arnold F. Wilkins, with the task of calculating how much energy would be required to damage an aircraft, or its crew — and whether or not such a ray could have already been produced by a rival nation.

After considering the physics, Wilkins admitted that the concept was theoretically sound, but that the power requirements were beyond anything that modern technologies would allow. The team concluded that it was truly an idea ahead of its time. So, on February 4, 1935, the two reported back to Tizard and Wimperis conceding there was simply no way for anyone to build a death ray.

A less unpromising problem

Undaunted by their failure to develop such a weapon, the Air Ministry continued to consult Watson-Watt and Wilkins about the looming bomber problem — and for good reason. It was during their work on the death ray when Wilkins realized that radio-detection might be, in his words, a "less unpromising problem". Specifically, Wilkins wondered if transmitting a beam at an object could still yield some positive results — albeit something a bit more benign.

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He remembered receiving notices from Post Office engineers claiming that aircraft flying in the vicinity of BBC masts were causing disturbances to radio signals — what engineers referred to as the ‘fluttering' effect. Wilkins theorized that, with the right equipment, it might be possible to develop an aircraft detection system by transmitting and receiving a re-radiated signal back from an incoming plane. It was a solution to the bomber problem that wasn't nearly as exciting as the death ray — but it was a very promising line of inquiry nonetheless; the ability to detect incoming planes without actually having to visually see them had the potential to irrevocably alter the nature of air warfare.

On February 12, 1935, the team presented their proposal for an air defense system to the Air Ministry, in which Watson-Watt noted that, "Although it was impossible to destroy aircraft by means of radio waves, it should be possible to detect them by radio energy bouncing back from the aircraft's body."

Unimpressed with their document, Air Vice Marshal Dowding demanded a demonstration. Happy to oblige, Watson-Watt and Wilkins set up an experiment at Daventry in Northamptonshire where they flew an old RAF bomber back and forth between two BBC radio masts. Huddled inside a small van with an assistant, Wilkins was able to track the position of the plane by monitoring a tiny glowing green line that flared and swelled on a crude cathode-ray tube display.

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The experiment worked; Watson-Watt declared that Britain "has become an island once more."

Their finest hour

They called their invention RDF (Radio Detection Finding), or what the Americans would later call radar (RAdio Detection and Ranging) — a breakthrough that forever changed the nature of air warfare, and eventually, the course of World War II.

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Radar proved to be an indispensable element of defense during the Battle of Britain in which Nazi bombers relentlessly attacked the U.K. in the summer and autumn months of 1940. By the end of their failed campaign, Germany had lost 1,184 planes to enemy action — nearly half of their entire fleet. Unable to establish air superiority, Hitler canceled his landing invasion plans and instead set his sights on Russia.

There is no understating the importance of radar in accounting for the British success, a country that would have suffered far more severely without it — and all thanks to a line of scientific inquiry that didn't quite lead where expected.